A veil can symbolize darkness, hidden knowledge, or the barrier between spirit and matter. A veil can represent truths that are keep hidden from the unworthy. It can also represent protection from something that can be harmful. It can represent the illusionary nature of the material world. A veil divides heaven from earth. 
    A veil can also represent submission to authority or submissiveness in general as with a nuns veil representing submission to God or the bridal veil representing the bride's submission to the groom. It also represents sacrifice and death since people who were being sacrificed or put to death usually had a veil over the face or head. A veil can represent suppression of personality, of self, of ego, to better serve the group. 
    In Christianity, a veil also represents chastity, modesty, and the renouncing of materialism.  The Arc of the Covenant was stored behind a veil for protection of the people near it. 
    In ancient Egypt, the veil of Isis hid the sacred mysteries of the universe. 
    In Islam, a veil represents hidden knowledge and parting the veil represents a revelation. In Islamic art, the face of the prophet is always hidden by a veil. A veil also separates the believers from the infidels. God speaks revelation from behind a veil so the person receiving the revelation is not blinded by His countenance. 
    Veils are almost always something worn by woman. One exception is the Tuareg tribe of West Africa. The men of the tribe wear a veil over the face as protection from evil spirits. It also does a good job of keeping the desert sand out of their nose and mouth.